The pollination ecology and reproductive phenology of a dioecious palm, Chamaedorea alternans were studied at Los Tuxtlas Biological Station in Veracruz state, Mexico during the 1995-96 flowering season. The sexes flower synchronously from October to January. Field observations investigated reproductive phenology, flower visitors and inflorescence and fruit production. Males produce more flowers and inflorescences than females. Seed-set was 13%, indicating low reproductive efficiency. Individual plants showed a great variation in number of inflorescences produced. Five female and eight male plants (out of 25 and 37 plants, respectively) produced 45% of all inflorescences in the population studied. These five females also produced c. 75% of all fruits. Seed production did not show significant differences between insect-excluded and open-pollinated inflorescences, in experiments to test the efficiency of wind pollination. Flowers of this species are wind-pollinated but a great activity of undetermined species of thrips (Thysanoptera) was observed in male inflorescences.
